2026-11-12 · Technical note
Solvent-Based vs Solvent-Free Laminating Adhesives: How to Choose
The practical differences between solvent-based and solventless polyurethane lamination, and which line conditions decide the choice.
Both systems bond two webs with a polyurethane adhesive. The difference is how the adhesive gets to the nip, and that difference drives everything else: line configuration, cost structure, process control and the defects you will spend your time chasing.
The two processes
Solvent-based. The adhesive is dissolved in organic solvent, applied to the primary web, and the solvent is evaporated in a drying tunnel before the second web is nipped in. The dried adhesive film is what bonds.
Solvent-free. A two-component adhesive with no solvent is applied warm, at 100% solids, and the webs are combined immediately. Nothing evaporates, so there is no tunnel and no solvent recovery.
Where solvent-based still wins
- Low coat weight on thin films. Solvent lets you lay down a very thin, even film.
- Older lines. A conventional laminator with a tunnel is a solvent-based machine.
- Wide process window. Small errors in ratio or temperature are more forgiving.
- Heat and chemical resistance. Retort and aggressive fills are well served by established solvent-based grades.
Where solvent-free wins
- No solvent cost or recovery. The environmental and permit argument is usually the trigger.
- Energy. No drying tunnel means a large drop in gas or electricity per metre.
- Footprint. A solventless line is shorter and needs no recovery plant.
- No residual solvent. Relevant for sensitive food-contact applications.
What solvent-free demands
Control. The mix ratio has to be accurate, the adhesive temperature has to be held, and line speed has to respect the wet-out time available before the nip. When one of those drifts the result is not a visible defect on the reel — it is delamination three days later in a finished pouch, which is the most expensive way to find out.
How to decide
| Question | Points toward |
|---|---|
| Is there a drying tunnel and solvent recovery? | Solvent-based |
| Is retort or aggressive fill involved? | Solvent-based, retort grade |
| Is solvent cost or permit the pressure? | Solvent-free |
| Is coat weight unusually low on thin film? | Solvent-based |
| Is the line already solventless? | Solvent-free |
The trial is the answer
No table decides this. Run both on the actual line, with the actual structure, and check bond strength after the full cure — not after an hour. The system that holds at 72 hours and through the fill is the one to standardise.